找出满足条件的圈

public class Solution {
    public void DFS(char[][]board,int row,int col){

      if(row<0||row>(board.length-1)||col<0||col>(board[0].length-1))
        return;
      if(board[row][col]=='O'){

          board[row][col]='*';
          DFS(board,row-1,col);
          DFS(board,row+1,col);
          DFS(board,row,col-1);
          DFS(board,row,col+1);
      }
    }

    public void solve(char[][]board){
      if(board.length<=0)  return;
      int row=board.length;
      int col=board[0].length;
      for(int i=0;i!=row;i++){
        DFS(board,i,col-1);
        DFS(board,i,0);
      }
      for(int i=0;i!=col;i++){
        DFS(board,0,i);
        DFS(board,row-1,i);
      }
      for(int i=0;i!=row;i++)
        for(int j=0;j!=col;j++)
        {

          if(board[i][j]=='O') board[i][j]='X';
          if(board[i][j]=='*') board[i][j]='O';

        }

    }

    public static void main(String[]args){
       // System.out.println("Hello");

    }
}